Multiresolution Modifier and N-gons
What I would suggest is turning the faces into quads or tris, like by poking (Ctrl+P). I don't know how exactly you want to save your original topology, but this shouldn't visibly change anything from the intended shape. 

Alternatively, if you're sure nobody will ever look up the nostrils (if this is a demo render, etc) then you could just remove the faces. however, if you're planning on texturing it open holes in the geometry can cause problems for volumetric or subsurface shaders.